If you were able to run CAL 0 with the inputs shorted, then security is not an issue.
After that, try CAL 10.xxxxxx whatever the value is. I think overload means the expected value is out of range. On Sat, Nov 18, 2017 at 3:58 PM, Randy Evans <[email protected]> wrote: > When I try to execute a 10V cal, I get an error code "209 HARDWARE FAILURE > - - INTERNAL OVERLOAD:31" I suspect that the unit has a different security > code than 3458. I can't change it without opening up the unit, which I > don't want to do unless I decide to keep it. Do you have any other > suggestions on how to check the A9 card? > > On Sat, Nov 18, 2017 at 11:17 AM, Randy Evans <[email protected]> > wrote: > > > Illya, > > > > That is a great idea. I will give it a try. > > > > Thanks > > > > On Sat, Nov 18, 2017 at 4:47 AM, Illya Tsemenko <[email protected]> wrote: > > > >> Since you have 732A, testing should be easy enough. Calibrate faulty > >> meter for zero and DCV 10V to 732A, record CAL? 2,1 value. This is your > LTZ > >> output. Then leave it running for few days to drift away and calibrate > >> again to same 732A. Check CAL? 2,1 again. Calculate the difference and > if > >> it matches output drift (that 1.1ppm/day you mention) - you can be 80% > sure > >> that A9 is a problem. Other 19% go to A1 and A3 circuits, as 7V is not > used > >> directly in the meter, and there are still gain parts to get +12 and > >> -12VREF on A3 and 10Vish bipolar levels on A1. If your CAL? 2,1 stays > same > >> (within 0.3ppm) then A9 is fine. > >> > >> > >> On November 18, 2017 12:59:53 PM GMT+08:00, Randy Evans < > >> [email protected]> wrote: > >>> > >>> I just received an Agilent 3458A that has a problem with noise and a > >>> drifting voltage measurements. I am using two Fluke 732As to compare > >>> absolute voltage measurements over time against the Agilent and an HP > >>> 3458A. The HP unit has a new A3 ADC card and seems to be very stable > and > >>> low noise, so is being used for comparison. I have been doing > simultaneous > >>> absolute voltage measurements and DC Cal Constant measurements several > >>> times a day and then calculating the drift rates of the two units > using the > >>> HP Service Note 18 procedure. > >>> > >>> > >>> > >>> The results indicate the Cal Constant drift rate of both units is very > >>> similar and within spec per Service Note 18. However, the absolute > value > >>> measurements show the Agilent unit changing 1.1 ppm over a day whereas > the > >>> HP unit is within a tenth of a ppm over a day. In my way of thinking > the > >>> Cal Constant procedure assumes the voltage reference board in the > 3458A is > >>> stable, hence the absolute value reading should remain essentially > constant > >>> after each ACAL DCV, which is the case with the HP unit. Since the > Agilent > >>> unit shows a steady drift in the absolute reading, this would indicate > to > >>> me that the voltage reference board is likely the cause of the > problem, and > >>> is also likely the cause of the noisy readings. If so, this is a > >>> “relatively” easy fix (I have several 3458A voltage reference boards, > one > >>> of which has been continuously powered up for several years). > >>> > >>> > >>> > >>> The issue is that I have to make a decision to keep or return the > Agilent. > >>> It has a cal seal on it and if I open the unit up to change the voltage > >>> reference board, I own it and can’t return it. I would appreciate an > >>> opinion from the members of the group as to what they think the odds > are > >>> that the voltage reference board is the source of the problems with the > >>> Agilent 3458A. > >>> > >>> > >>> > >>> Thanks, > >>> > >>> > >>> > >>> Randy Evans > >>> > >>> > > > _______________________________________________ > volt-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/volt-nuts > and follow the instructions there. > _______________________________________________ volt-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
